A conventional fuel injection valve is described in German Patent Application No. 43 25 842.
This conventional fuel injection valve is a typical mass-produced valve (along with its individual parts) which is simple and inexpensive to manufacture and has a reliable performance. The casing of this conventional fuel injection valve includes a number individual parts joined together. The coupling and the valve seat carrier are typical joined using lathe procedure and are internally and externally machined. This conventional design provides relatively thick walls in the fuel injection valve, and causes a considerable consumption of material and a substantial weight. It may be feasible to reduce the wall thickness by using an optimal machining process. However, such process would be very labor-intensive and time-consuming and leads to high manufacturing costs.
In addition, special design requirements apply to a fuel injection valve with a conventional electromagnetic actuation for an opening movement of a valve closing body to provide conducting elements of ferromagnetic material for a electromagnetic coil to conduct a magnetic flux. The coupling of the conventional fuel injection valve with its downstream cylindrical end extends as a coil core passing through the magnetic coil. The valve seat carrier extends with an upper hollow cylindrical end section to a downstream end of the coil bobbin, an intermediate ring being arranged between the coil core and the valve seat carrier. In order to provide a guide for the magnetic flux for the upstream end of the magnetic coil and its outer periphery, at least one conducting element bridging the magnetic coil is externally provided in the conventional fuel injection valve. The individual parts of the fuel injection valve described above are tightly joined together by several mechanical joints, such as welds, with plastic extrusion coating being provided to sheath great lengths of the conducting element, the coupling and the valve seat carrier as an additional casing part to form the casing. This results in a multiple-part design.
German Patent Application No. 44 26 006 mentions that the valve needle and valve closing body of the conventional fuel injection valve described above can be manufactured from a one-piece deep-drawn part.